Air heater



March 14, 1939. H. w. SCHRAMM AIR HEATER Filed Sept. 28, 1938 Snnentor /7. Mfia/va/mz Patented Mar. 14,1939

PATENT OFFICE AIR HEATER Henry W. Schramm, Toledo, Ohio, assignor to Surface Combustion Corporation, Toledo, Ohio,

a corporation-oi New York Application September 28, 1938, Serial No. 232,059

comma The present invention relates to apparatus for heating air by admixture with hot products of combustion; and the object of the invention is to provide a heater that shall be simple in construction and well adapted for its intended purpose.

In the accompanying drawing wherein the preferred form of the invention is shown- Fig. 1 is a longitudinal sectional view of the heater;

Fig. 2 is an end view of the heater with a portion in section on line 2-2 of Fig. 1, and

Fig. 3 is a schematic view illustrating how the heater may be utilized for supplying heated air to an industrial oven.

The improved heater comprises a structure I having a flow passage 4' extending therethrough for the air to be heated, the ends of said passage being adapted to be coupled to an air supply pipe 5 and an outlet pipe 6, respectively; the air being heated as it flows through said passage by admixture with hot products of combustion produced by pressure burners I firing into said passage in a manner to flow around in the passage for reasons hereinafter appearing.

Said structure 4 comprises an external metal casing 8 having inwardly directed side flanges 8'; a layer of insulating material 9 disposed against the inside face of said casing material 9; a layer of refractory material Ill disposed against the inside face of layer 9, and a refractorybushing l I which terminates short of the burner outlets whereby to provide a setback I! wherein the flaming gases from-the burners are initially protected against the chilling eflect of the incoming air for a long enough time to insure complete combustion of the fuel in the flaming gases. The setback I! therefore constitutes, as it were, a ringlike combustion chamber whose inner side is in open communication with the air passage 4.

It is preferred that the setback I! take the form of a channel between the ends of the passage 4 and to this end there is provided another refractory bushing II in axial alinement with the bushing II, the internal diameter of the bushing l3, being preferably somewhat greater than that of the bushing ll.

The burners I may be of any preferred type of pressure burner. As shown, the burner comprises a nozzle ll to which a preformed mixture of air and gas is supplied by a pipe II, the nozzle discharging into'a refractory tunnel it arranged to discharge tangentially into the setback l2. ranged in a circle and fire tangentially into the Due to the fact that the burners are ar- (c ass-19) setback 12, the flames from one burner will ignite the next adjacent burner thereby making it unnecessary to provide special igniting means for each burner. Any preferred means for initially igniting one of the burners may be employed. 5 As illustrative of a simple way of igniting one of the burners, ll indicates a lighting hole which leads into the burner tunnel it from outside of the heater, the top of the hole being normallyclosed by a seal It. To light the burner the seal 1. is removed and a flare inserted into the hole. The number of burners employed will of course depend upon the capacity of the heater. v

Referring to Fig. 3 which shows one way of applying the heater to an industrial heating oven, II It indicates the oven which is to be heated by the hot air from the heater 4. In the pipe 5 which delivers air to the heater is a fan or blower 20 adapted to withdraw the air from the oven by way of a conduit 2| and to deliver it to the heater 1; ior reheating.

From the foregoing description it will be seen that the heater of the present invention offers practically no resistance to the flow of air therethrough and that it is well adapted for insertion 3; in a duct system of which the pipes 5 and 8 may be considered a part.

What I claim as new is:

1. Apparatus for heating air by admixture with hot gases of combustion comprising, in com- ,0 bination, a structure having a flow passage therethrough for the air to be heated, said passage inwar'dly from its air intake end having a peripheral setback, and means for discharging hot gases of combustion into said passage along the wall of 3| said setback.

2. Apparatus for heating air by admixture with hot gases of combustion comprising, in combination, astructure having a flow passage therethrough for the air to be heated, said pas- 4o sage inwardly from its air intake end having a peripheral setback, and means for discharging hot gases of combustion into said setback in a direction to flow around therein coaxial with said passage.

3. Apparatus for heating air by admixture Y with hot gases of combustion comprising, in combination, a structure having a flow passage therethrough for the air to be heated, said passage intermediate its ends having a peripheral channel, 50 and means for discharging hot gases of combustion into said channel. I

4. Apparatus for heating air by admixture with hot gases oi combustion comprising, in combination, a structurehaving a flow passage thereas through for the air to be heated, said termediate its ends ha a =,-pherai channel, and means for discharging hot of combustion into said channel in a direction to flow around therein coaxial with said passage.

5. Apparatus for heating air by admixture with hot gases of combustion comprising. a structure forming a flow passage for said air, said passage beginning at a point remote from the air inlet end thereof being of greater cross-sectional 'area than the preceding portion whereby to form a setback in said passage, and a burner firing into said setback in a manner to cause the hot gases initially to wipe the walls thereof.

6. Apparatus for heating air flowing through a conduit by admixture with hot gases of combustion comprising a casing adapted to be inserted in said conduit, said casing being internally lined with refractory material to form 9. cylindrical air passage which forms in efl'ect a continuation of said conduit, said passage being recessed intermediate its ends to form an annular channel therein, and a burner firing tangentially into said channel whereby the hot gases from said burner initially encircle the air flowing through said passage.

HENRY W. SCHRAMM. 

